1. Field
This disclosure generally relates to installation/processing systems for installing expandable members into holes in workpieces and/or cold expanding holes in workpieces.
2. Description of the Related Art
Conventional installation tools are used to install bushings in holes within workpieces. These installation tools often have an expansion mandrel with an enlarged tapered portion used to expand the bushing. To radially expand the bushing, the expansion mandrel is inserted into an opening in the bushing. The bushing and mandrel are simultaneously inserted into a hole in a workpiece. When the bushing is positioned in the hole of the workpiece, the enlarged tapered portion of the mandrel extends outwardly from the backside of the workpiece. These types of installation tools thus require an adequate amount of backside clearance and are unsuitable for installing bushings in non-through holes, blind holes, or other holes having limited backside clearance.
To expand the bushing, the enlarged tapered portion of the mandrel is forcibly pulled axially through the opening of the bushing until an interference fit is formed between the bushing and workpiece. Unfortunately, relatively high frictional forces can be generated as the mandrel is moved through the bushing. These forces may cause the bushing to move relative to the workpiece, thus resulting in improper positioning of the installed bushing. Additionally, as the mandrel is pulled through the bushing, the outer surface of the mandrel can abrade the sidewall of the bushing's opening, thereby reducing the quality of the installed bushing.
Other installation tools use a threaded installation member to install a partially collapsible fastener element. The partially collapsible fastener element is inserted into a through hole in a workpiece until a first flange at a trailing end of the fastener element is in contact with a front face of the workpiece. Unfortunately, a collapsible portion of the fastener element has to extend outwardly from the backside of the workpiece, thus requiring a through hole having sufficient backside clearance.
Once the fastener element is positioned in the workpiece, an externally threaded end of the threaded installation member is inserted into an opening in the fastener element from the front side of the workpiece. The installation member is threadably mated with internal threads of the fastener element such that both the installation member and fastener element extend beyond the backside of the workpiece.
A tubular mandrel surrounding the installation member is moved into contact with an entrance of the opening in the fastener element. An actuator (e.g., pusher, puller) device retracts the installation member through the tubular mandrel to cause the collapsible portion (e.g., a reduced thickness wall portion) of the fastener element to collapse and form a second flange on the backside of the workpiece. The workpiece is thus sandwiched between the first and second flanges of the fastener element. Unfortunately, during this process, the actuator device is pulled against the front surface of the workpiece and may deform, mar, or otherwise degrade the front surface of the workpiece.
The tubular mandrel is moved axially into the opening of the fastener element causing radial expansion of a portion of the fastener element. The portion of the fastener element is radially expanded against the sidewall of the opening to form an interference fit. During this expansion process, the mandrel directly contacts and slides against the fastener element and, consequently, can undesirably abrade and damage the surface of the fastener element.
Consequently, conventional installation tools may not adequately meet certain quality and installation needs.